Electronic organs have been known for many years and for most of the that time have used analog tone generators of one sort or another. In so called additive or synthesizing organs it has been the practice to add together a large number of harmonically related sine waves to produce resultant complex waves. In the so called formant type of organ complex waves have been generated which have thereafter been filtered to remove undesired harmonic and inharmonic partials, and thereby to simulate a desired wave form.
In more recent years the patent art is replete with disclosures of digital organs in which computer techniques are utilized to generate or establish desired wave forms.